Red Blood Cell Distribution Width Can Predict Vasculitis Activity and Poor Prognosis in Granulomatosis with Polyangiitis

PURPOSE: We investigated whether red blood cell distribution width (RDW) predicts vasculitis activity based on Birmingham vasculitis activity score (BVAS) or BVAS for granulomatosis with polyangiitis (GPA) at diagnosis and poor prognosis during follow-up in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). MATERIALS AND METHODS: We reviewed the medical records of 150 patients with AAV. We defined severe GPA as BVAS for GPA ≥7 (the highest quartile). Correlation and standardised correlation coefficients were analysed by linear regression tests. The differences between groups were evaluated by Mann-Whitney test. Relative risk (RR) was assessed by chi square test and Cox hazards model. RESULTS: RDW was correlated only with the vasculitis activity of GPA among patients with AAV. An increase in RDW was associated with the absence of ear nose throat (ENT) manifestation, but not proteinase 3-ANCA. Significant differences were noted in cumulative refractory free survival according to RDW ≥15.4% (p=0.007) and the absence of ENT manifestation (p=0.036). Multivariate Cox hazards analysis identified RDW ≥15.4% as the only significant predictor of refractory disease in GPA (RR 17.573). CONCLUSION: RDW predicts vasculitis activity in GPA, and RDW ≥15.4% at diagnosis may increase the risk of severe GPA at diagnosis and predict refractory diseases during follow-up.